Natural products are organic compounds obtained from
A petroleum sources
B living organisms
C synthetic laboratories
D inorganic minerals
Natural products are isolated from plants, animals, or microorganisms.
Which of the following is a natural product
A polyethylene
B aspirin
C morphine
D PVC
Morphine is obtained from opium poppy.
Alkaloids are
A acidic compounds
B nitrogen-free compounds
C nitrogen-containing natural products
D carbohydrates
Alkaloids contain basic nitrogen atoms.
Which of the following is an alkaloid
A glucose
B caffeine
C starch
D cellulose
Caffeine is a naturally occurring alkaloid.
Morphine is used as
A antibiotic
B analgesic
C antiseptic
D antipyretic
Morphine is a strong pain-relieving drug.
Nicotine is obtained from
A tea leaves
B coffee beans
C tobacco
D cocoa
Nicotine is the chief alkaloid of tobacco.
Which alkaloid acts as a stimulant
A morphine
B quinine
C caffeine
D atropine
Caffeine stimulates the central nervous system.
Quinine is used for the treatment of
A cancer
B malaria
C tuberculosis
D diabetes
Quinine is an antimalarial alkaloid.
Terpenes are natural products derived from
A amino acids
B fatty acids
C isoprene units
D nucleotides
Terpenes follow isoprene rule.
Which compound is a terpene
A glucose
B cholesterol
C limonene
D morphine
Limonene is a terpene found in citrus oils.
Essential oils mainly contain
A alkaloids
B terpenes
C proteins
D carbohydrates
Terpenes give characteristic fragrance.
Steroids are derived from
A carbohydrates
B amino acids
C fatty acids
D triterpenes
Steroids are formed from isoprene units.
Cholesterol belongs to which class
A alkaloid
B terpene
C steroid
D vitamin
Cholesterol has steroid nucleus.
Hormones are
A enzymes
B carbohydrates
C chemical messengers
D polymers
Hormones regulate physiological functions.
Insulin is a
A carbohydrate
B lipid
C protein hormone
D steroid hormone
Insulin is a polypeptide hormone.
Adrenaline is derived from
A carbohydrate
B amino acid
C fatty acid
D nucleotide
Derived from tyrosine.
Enzymes differ from ordinary catalysts because they
A are consumed
B are less specific
C work under mild conditions
D increase temperature
Enzymes function at physiological pH and temperature.
Coenzymes are usually
A inorganic ions
B carbohydrates
C vitamins or vitamin derivatives
D proteins
Example: NAD⁺, FAD.
Apoenzyme refers to
A enzyme without cofactor
B enzyme with cofactor
C inactive enzyme
D denatured enzyme
Apoenzyme alone is inactive.
Holoenzyme is
A apoenzyme only
B coenzyme only
C apoenzyme + cofactor
D denatured enzyme
Complete active enzyme.
Competitive inhibition occurs when inhibitor
A binds to enzyme permanently
B binds to active site
C binds to allosteric site
D destroys enzyme
Competes with substrate.
Competitive inhibition can be overcome by
A decreasing substrate concentration
B increasing substrate concentration
C changing temperature
D denaturing enzyme
Substrate outcompetes inhibitor.
Non-competitive inhibitor binds to
A active site
B substrate
C allosteric site
D product
Alters enzyme structure.
Which process releases energy in living cells
A photosynthesis
B respiration
C digestion
D transpiration
Breakdown of glucose releases energy.
ATP stores energy in
A C–C bonds
B hydrogen bonds
C phosphoanhydride bonds
D glycosidic bonds
High-energy P–O–P bonds.
Metabolism includes
A digestion only
B catabolism only
C anabolism only
D both anabolism and catabolism
Building and breakdown reactions.
Anabolic reactions are
A energy releasing
B energy consuming
C spontaneous
D oxidative
Require ATP.
Catabolic reactions are
A energy consuming
B energy neutral
C energy releasing
D polymer forming
Breakdown of complex molecules.
Glycolysis occurs in
A mitochondria
B nucleus
C cytoplasm
D ribosome
First step of respiration.
Krebs cycle occurs in
A cytoplasm
B nucleus
C mitochondria
D chloroplast
Aerobic respiration pathway.
Which molecule carries electrons in respiration
A ATP
B NAD⁺
C glucose
D oxygen
Reduced to NADH.
Photosynthesis occurs in
A mitochondria
B chloroplast
C nucleus
D cytoplasm
Contains chlorophyll.
Chlorophyll absorbs light mainly in
A green region
B red and blue region
C yellow region
D infrared region
Green light is reflected.
Which is NOT a natural polymer
A cellulose
B starch
C nylon
D proteins
Nylon is synthetic.
Natural rubber is a polymer of
A ethene
B propene
C isoprene
D styrene
cis-1,4-polyisoprene.
Enzymes are affected by pH because
A bonds break
B active site shape changes
C substrate concentration changes
D enzyme evaporates
pH alters ionisation state.
Optimum pH of pepsin is
A neutral
B alkaline
C acidic
D basic
Works in stomach.
Which biomolecule is main energy source
A proteins
B lipids
C carbohydrates
D nucleic acids
Glucose is primary fuel.
Lipids are insoluble in
A ether
B benzene
C chloroform
D water
Lipids are hydrophobic.
Fats are esters of
A fatty acids and glycerol
B amino acids and glycerol
C carbohydrates and acids
D proteins and lipids
Triglycerides structure.
Unsaturated fats contain
A single bonds only
B double bonds
C triple bonds
D aromatic rings
C=C bonds present.
Hydrogenation of vegetable oil produces
A butter
B ghee
C margarine
D soap
Partial hydrogenation.
Rancidity of fats is due to
A oxidation
B reduction
C condensation
D polymerisation
Produces unpleasant smell.
Antioxidants prevent rancidity by
A increasing oxidation
B inhibiting oxidation
C increasing hydrolysis
D polymerisation
Scavenge free radicals.
Which vitamin acts as antioxidant
A vitamin A
B vitamin C
C vitamin D
D vitamin K
Prevents oxidative damage.
Enzymes show saturation because
A enzyme denatures
B substrate finishes
C all active sites are occupied
D temperature increases
Maximum velocity reached.
Michaelis constant (Km) indicates
A enzyme efficiency
B substrate concentration for half-max velocity
C reaction rate
D activation energy
Lower Km means higher affinity.
Enzymes are reusable because
A they are stable
B they are not consumed
C they are proteins
D they are soluble
Regenerated after reaction.
Which molecule acts as biological catalyst
A vitamin
B hormone
C enzyme
D lipid
Speeds up biochemical reactions.
Correct statement is
A Alkaloids are carbohydrates
B Enzymes work at extreme temperatures
C Natural products are obtained from living sources
D Vitamins are polymers
Fundamental definition.